Vibration isolation member

ABSTRACT

A vibration isolation member comprising an inner member comprising an outer periphery having a first dimension; an outer member comprising a base and a shroud that extends away from the base, the shroud adapted to overlay the inner member, said shroud defining an inner periphery having a second dimension, the second dimension being less than the first dimension; and a resilient member constrained between the shroud and the inner member, whereby the vibration isolation member provides iso-elastic dynamic stiffness and an interference between the inner and outer members in the event of a failure of the resilient member.

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.09/829,883 filed Apr. 10, 2001 now U.S. Pat. No. 7,316,389, the priorityto which is herein claimed and which is incorporated herein byreference.

FIELD OF THE INVENTION

The invention relates to a vibration isolation member and moreparticularly the invention relates to a vibration isolation member thatprovides substantially equal dynamic stiffness in radial and axialdirections and comprises an outer member with an inner periphery, aninner member with an outer periphery and a resilient member joining theinner and outer members wherein the dimensions of the inner and outerperipheries provide for an interference therebetween in the event of afailure of the elastomer.

BACKGROUND OF THE INVENTION

Vibration isolation members are frequently used in aircraft interiorapplications to reduce the vibration and noise exposure to delicate andsensitive instrumentation and also to passengers in the aircraft cabin.In aircraft applications the vibration isolation members must providethe requisite vibration reduction with a minimum size and weightvibration isolation member.

One means for effectively reducing such exposure to noise and vibrationis to use a vibration isolation member that has iso-elastic stiffnessproperties. A vibration member that is iso-elastic has equal stiffnessin the axial and radial directions. Iso-elastic stiffness permits thevibration isolator to provide dependable performance in any orientationand maximize vibration reduction for a given installation. A vibrationisolation member that does not provide such iso-elastic stiffnessproperties will transmit vibration more efficiently in one or moredirections, compared to an iso-elastic vibration member having the sameminimum stiffness.

Additionally, it is desirable to include a mount fail-safe feature thatprevents the mount from separating in the event the mount fails underloading. Several prior art mounts provide fail safe features thatfunction in a single axial direction however, such prior art mountstypically do not have two fail safe paths. Moreover, in vibrationisolation members that comprise iso-elastic members, the membersfrequently do not have a fail-safe or interference path that is definedby the components that comprise the mount. Rather the fail-safe featureis produced by adding washers or other discrete mechanical members tothe member. The additional components required to provide a fail safefeature in an iso-elastic vibration isolation member add weight andincrease the volume required to house the member in the aircraft.

The foregoing illustrates limitations known to exist in present devicesand methods. Thus, it is apparent that it would be advantageous toprovide a vibration isolator that provides iso-elastic stiffness incombination with fail safe feature and thereby solves one or more of theshortcomings of present isolation devices and methods. Accordingly, asuitable vibration isolation member is provided including features morefully disclosed hereinafter.

SUMMARY OF THE INVENTION

In one aspect of the present invention this is accomplished by providinga vibration isolation member that provides iso-elastic stiffness and atleast one fail-safe feature.

More specifically the vibration isolation member of the presentinvention comprises an inner member comprising an outer periphery havinga first dimension; an outer member comprising a base and a shroud thatextends away from the base, the shroud adapted to overlay the innermember, said shroud defining an inner periphery having a seconddimension, the second dimension being less than the first dimension; anda resilient member constrained between the shroud and the inner member,whereby the vibration isolation member provides iso-elastic stiffnessand an interference between the inner and outer members in the event ofa failure of the resilient member.

The inner member is unitary and is comprised of a stem and a seat wherethe seat includes a first surface, a second surface spaced from thefirst surface and a third surface that joins the first and secondsurfaces. The third surface is oriented at an angle relative to thefirst surface. The seat has a frustoconical configuration.

The outer member shroud may comprise a single segment or may comprise afirst segment, a second segment and a third segment, the second segmentjoining the first and third segments. The outer member first segment isoriented substantially axially, the third segment is orientedsubstantially radially and the second segment is oriented at an anglerelative to the first and second segments. The third surface of the seatis substantially parallel to the second segment of the shroud.

The foregoing and other aspects will become apparent from the followingdetailed description of the invention when considered in conjunctionwith the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of the vibration isolation member of thepresent invention.

FIG. 2 is a top view of the vibration isolation member of FIG. 1.

FIG. 3 is a longitudinal sectional view taken along line 3-3 of FIG. 2.

FIG. 4 is a longitudinal sectional view like the sectional view of FIG.3 illustrating a second embodiment vibration isolation member of thepresent invention.

FIG. 5 is a longitudinal sectional view like the sectional view of FIG.3 illustrating third embodiment vibration isolation member of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning to the drawing Figures wherein like parts are referred to by thesame numbers in the Figures, the first embodiment vibration isolationmember 10 of the present invention is disclosed in FIGS. 1, 2 and 3.

Generally, vibration isolation member 10 comprises an inner member 12,an outer member 14 and a resilient member 16 that joins the inner andouter members. The resilient member is constrained between the inner andouter members. The inner and outer members 12 and 14 are relativelyrigid. The vibration isolation member 10 is made from a conventionalmolding process well known to those skilled in the art and during themolding process the resilient member is bonded to the inner and outermembers. The resilient member 16 may be comprised of any suitablematerial however for purposes of the preferred embodiment of theinvention the resilient member is comprised of a silicone or a syntheticrubber.

As shown in the sectional view of FIG. 3, the isolator is adapted to beconnected between a support structure 18 such as an aircraft frame forexample, and a suspended body 20 which may be an interior aircraftinstrument or trim panel. The isolator 10 of the present inventionreduces the transmission of vibratory disturbances, which may be in theform of acoustic noise, between the support structure 18 and thesuspended body 20. The isolator also limits heat transfer between body20 and structure 18. Also shown in FIG. 3, the isolation member isjoined to the suspended body 20 by conventional fastener 22 that extendsbetween the body 20 and inner member 12; and is joined to the supportstructure 18 by fasteners 24 a, 24 b that extend through the outermember 14. The fasteners may be comprised of any suitable fastener wellknown to those skilled in the art including, but not limited to screwsor quick-connect fasteners. By these connections, the outer member 14remains substantially stationary during use and the inner member 12 maybe displaced in radial and axial directions represented by respectivedirectional arrows 25 and 26.

The relatively rigid inner member 12 is unitary and comprises an axiallyextending cylindrical stem 30 and frustoconical seat 32. As shown inFIG. 3, the seat includes first and second faces 34 and 36 joined byangled surface 38 that extends outwardly from face 34 to face 36. Thesurface 38 may extend at any suitable angle, Θ relative to face 34. Forpurposes of describing the preferred embodiment of the invention, theangle may be about 55°. The stem is made integral with the seat 32 atface 34 and the free end of the stem extends outwardly from the openingin the outer member 14 defined by inner periphery 62. Faces 34 and 36are circular, planar members that join the surface 38 at respectiveouter edges. The inner member includes an axially extending bore 40 thatextends through the stem and seat and is adapted to receive fastener 22previously described above. The seat defines an outer periphery 42 thatcomprises a diameter, D′. The extent of the inner member outer periphery42 is also represented in dashed font in FIG. 2. As shown in FIG. 3,when the member 10 is installed the seat is located proximate thesupport member 18. Additionally, as shown in FIG. 3, the surface 36 islocated a distance away from the support structure 18 to allow fordisplacement of inner member 12 when the isolation member 10 experiencesa vibratory disturbance.

The relatively rigid outer member 14 is unitary and comprises asubstantially planar flange or base 50 with bores 52 a and 52 b that areadapted to receive fasteners 24 a and 24 b as described hereinabove. Thebase 50 is made integral with an annular shroud 54 that overlays seat32. The shroud comprises a first segment 56 that extends in the axialdirection defined by arrow 26, a second segment 58 that extendssubstantially parallel to surface 38, and a third segment 60 thatextends in the radial direction defined by arrow 25. The second segment58 joins the first and third segments 56 and 60. See FIG. 3. Althoughthe second segment is shown at an orientation that is substantiallyparallel to surface 38 it should be understood that although such aparallel configuration is preferred the second segment could be orientedat any relative angle and do not have to be parallel.

Third segment 60 terminates at inner periphery 62 that defines diameter,D″. As shown in FIGS. 2 and 3, the outer periphery 42 has a diameter D′that has a greater radial dimension than inner periphery 62 diameter,D″. In the event that resilient section fails, and the seat is displacedaxially toward panel 20, an interference or fail-safe load path would becreated between the seat and the segment 60 preventing furtherdisplacement of seat outward from the outer member. Thus the innermember would be captured by the outer member. As shown most clearly inthe sectional view of FIG. 3, to ensure that the desired interference isproduced between the seat and shroud, the inner periphery 62 mustterminate radially inwardly from the outer periphery 42.

During molding, resilient member 16 is bonded to the surface 38 and alsoto the inner surface of second segment 58. Additionally, the moldingprocess produces relatively thin skin segments bonded along the innersurface of third segment 60 and inner periphery 62, stem 30 and surface34, outer periphery 42 and along portions of the inner surfaces offlange 50 and first segment 56. Apart from the skins, the main portionof the resilient member 16 has a substantially trapezoidal crosssection.

The vibration isolation member 10 of the present invention providesiso-elastic stiffness. The term “iso-elastic” means that the isolationmember 10 has substantially the same stiffness in the axial and radialdirections for any applied load. Because the resilient member 16 isconstrained between the inner member 12 and outer member 14 theresilient member 16 experiences combined shear loads and loads in eithertension or compression regardless of the direction and magnitude of theload applied to the vibration isolation member 10.

The vibration isolation member 10 of the present invention provides adouble fail safe feature that captures the inner member and maintains itin the chamber 80 defined by the outer member and the support structure18. Failure of the elastomer member 16 or failure of the bonds betweenmember 16 and either inner member 12 or outer member 14 will not permitthe inner member to relocate outside of the outer member. The innermember is captured by either the structural panel 18 or by theinterference between the seat and segment 60 as described hereinabove.Therefore, in order for the inner member seat to become displaced fromthe chamber 80, failure of the inner member, outer member fasteners orstructural member must occur in addition to the resilient memberfailure. Additionally, in the event the resilient member 16 fails theseat will not be displaced out of chamber 80. The suspended body 20 willengage the rigid outer member while the seat will interfere with theinner member. Additionally, the structural member will impede additionalaxial displacement of the seat towards member 20. In this way, the mountof the present invention provides double fail-safe feature incombination with its iso-elastic stiffness.

A second preferred embodiment vibration isolation member 70 is shown inFIG. 4. The alternate embodiment mount 70 includes relatively rigidinner member 72 comprises stem 30 and seat 32 which defines angledsurface 38. The stem 30, seat 32 and surface 38 as well as the othercomponents and features are the same as those described hereinabove inconjunction with first embodiment vibration isolation member 10. In thesecond embodiment mount 70, the stem 30 and seat 32 may be made directlyintegral. The inner member 72 does not include surface 34 joining thestem and seat. The second embodiment member 70 includes the doublefail-safe feature and also includes an iso-elastic stiffness.

A third preferred embodiment vibration isolation member 75 isillustrated in FIG. 5. The alternate embodiment mount 75 includesrelatively rigid outer member 76 with shroud 78. As shown in FIG. 5, theshroud member is comprised of a hollow cone with a wall comprised of asingle angled segment, that terminates at an inner periphery 62. Asdescribed in conjunction with first embodiment isolation member 10, theinner periphery 62 has a diameter D″ that is less than the diameter D′of the outer periphery 42 of the seat 32. The other components andfeatures of member 75 are the same as those described hereinabove inconjunction with first embodiment vibration isolation member 10. Thethird embodiment member 70 includes the double fail-safe feature andalso includes an iso-elastic stiffness.

It should be understood the use of outer member 76 and inner member 72are not limited to the isolation members shown in their respectiveembodiments but rather, outer member 76 may be combined with innermember 72 if desired.

While I have illustrated and described a preferred embodiment of myinvention, it is understood that this is capable of modification, and Itherefore do not wish to be limited to the precise details set forth,but desire to avail myself of such changes and alterations as fallwithin the purview of the following claims.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the invention withoutdeparting from the spirit and scope of the invention. Thus, it isintended that the invention cover the modifications and variations ofthis invention provided they come within the scope of the appendedclaims and their equivalents. It is intended that the scope of differingterms or phrases in the claims may be fulfilled by the same or differentstructure(s) or step(s).

1. A method of isolating a body and a structure comprising: providing astructure having a surface; providing a body located away from thestructure, said body having a body fastener location for isolationfastening to said body; providing a resilient member iso-elasticvibration isolation member with an outer member with a planar base and aconical shroud and with an inner member with an axially extending stem,said vibration axially extending stem fastened to said body at said bodyfastener location to provide a resilient connection between said outermember conical shroud and said body fastener location to reduce thetransmission of vibratory disturbances between the body and saidstructure and to provide an isolation of said body from said structure,the vibration isolation member inner member including a frustoconicalseat having an angled surface and an outer periphery diameter D′; saidouter member including a planar base with said conical shroud extendingaway from the planar base, the conical shroud extending to overlay theinner member outer periphery diameter D′, said conical shroud having anangled segment with an inner surface, said angled segment inner surfaceoriented substantially parallel to said angled surface of saidfrustoconical seat, said angled segment inner surface and saidsubstantially parallel angled surface of said frustoconical seat angledrelative to a radial direction axis and a perpendicular axial directionaxis extending in a direction along said axially extending stem withsaid perpendicular axial direction axis perpendicular to said radialdirection axis wherein extensions of said angled segment inner surfaceand said substantially parallel angled surface of said frustoconicalseat intersect both said radial direction axis and said axial directionaxis with said conical shroud defining an inner periphery diameter D″with said axially extending stem extending out through said innerperiphery diameter D″ along said perpendicular axial direction axisoutward towards said body fastener location with said stem fastened tosaid body, said inner periphery diameter D″ less than said outerperiphery diameter D′, said outer member planar base joined to saidstructure surface with said outer member conical shroud and saidstructure surface comprising a chamber with the inner member seatcontained within said chamber; and said resilient connection betweensaid outer member conical shroud and said body fastener locationconsisting essentially of a single resilient member constrained betweenthe conical shroud angled segment inner surface and the inner memberfrustoconical seat angled surface, said single resilient member having across section, said single resilient member cross section bonded to saidshroud angled segment inner surface and said inner member frustoconicalseat angled surface with said single resilient member cross sectioncontained within said chamber and between said shroud angled segmentinner surface and said inner member frustoconical seat angled surface,wherein said contained within single resilient member cross sectionbonded to said conical shroud angled segment inner surface and saidinner member frustoconical seat angled surface provides for iso-elasticdisplacement of said inner member in a radial direction along saidradial direction axis and in an axial direction along said axialdirection axis from said outer member with said frustoconical seat outerperiphery diameter D′ providing an interference with said conical shroudinner periphery diameter D″ to prevent a separation of the vibrationisolation member in the event of a failure of said resilient connectionconsisting essentially of said single resilient member cross sectioncontained within said chamber, wherein said single resilient membercross section isolates said body and said structure with saidiso-elastic vibration isolation member providing a substantially equaldynamic stiffness in the radial direction along said radial directionaxis and in the axial direction along said axial direction axis for anapplied load between the body and the structure.
 2. The method asclaimed in claim 1 wherein said inner member seat does not extend intosaid support structure plane surface.
 3. The method as claimed in claim2 wherein the support structure plane surface and said inner member seatare separated by a distance.
 4. The method as claimed in claim 1 whereinthe shroud is comprised of a single wall.